The present invention relates generally to holographic combiners, and more particularly, to holographic combiner edge sealing methods and materials.
Head up display combiners are an important product for use in aircraft flight applications. Military programs require flight ready combiners, and as such they must meet stringent design requirements. Without edge sealing, combiners of the type currently produced will not meet qualification test requirements relating to water absorbancy. Various methods have been demonstrated in the art to achieve water absorbancy protection for holograms, but these have been shown to provide insufficient protection. Such methods include coating the combiners with a parylene thin film coating, or coating the perimeter of combiners with unimproved thermoset adhesives.
Accordingly, it is an objective of the present invention to provide for hologram combiners and edge sealing methods therefor that achieve acceptable water protection for the holograms contained therein.